(a) Field of the Invention
The invention relates to a rolling press member for power switch, and more particularly, to a rolling press member having a roller at an end portion of the press member placed in a center column of a button, thereby elevating displacement smoothness of a contact plate at an interior of a switch housing.
(b) Description of the Prior Art
Switches are generally provided for various kinds of electric appliances or mechanical apparatus as controlling means for shutting down or conducting power supplies. To be more precise, these switches are utilized for facilitating turning on or off power supplies of these equipments. Referring to FIG. 7 showing a conventional fundamental structure of a common switch, a switch housing A is pivotally disposed with a button B at an upper portion thereof. The button B has a center column B1 at a bottom center thereof. An interior of the center column B1 is provided with an elastic member B2 for pushing against an elastic press member B3, which is pressed against and joined with an arched contact plate C at a bottom portion of the switch housing A. The contact plate C has symmetrical apertures C1 at edges of a middle section thereof, and is erected at a live wire conducting strap D disposed at the bottom portion of the switch housing A via the apertures C1. The contact plate C further has a contact point C2 at one end thereof, and the contact point C2 is in contact with another live wire conducting strap E when being moved downward. As shown in the diagram, in occurrence that the button B is provided with an additional power indication lamp F, the elastic member B2 has two ends thereof in contact with the power indication lamp F and the arch contact plate C along with the press member B3 to form a live wire route. The button B is also provided with an elastic member G connected with the power indication lamp F. The elastic member G is in contact with an earth wire conducting strap H to serve as an earth route of the power indication lamp F. Using the aforesaid structure, pressing of the button B impels swaying of the center column B1 to change a contact status of the contact point C2 of the contact plate C relative to the live wire conducting strap E using the elastic and contractible press member B3, so as to appropriately control conducting or shutting off of the switch. In addition, under a conducted status, the power indication lamp F in the button B is lit up.
However, after thorough study, it is observed that elastic contraction of the press member B3 relative to the contact plate C is performed from swaying of the center column B1 from pressing the button B. Wherein, before being impelled, a status of the hollow press member B3 being contact with the contact plate C is regarded as a “direct contact”, meaning that a resistance against sliding movements is comparatively larger with more likely wear from abrasion. Meanwhile, in order to maintain the press member B3 remaining in contact with the elastic member B2 when being pushed downward, it is essential that contraction displacements of the press member B3 relative within the center column B1 be quite smooth in all time, and thus the press member B3 is applied with grease I. Nevertheless, as shown in the diagram, the grease I is often accumulated between a lower end of the center column B1 and the outer surfaces of the press member B3, and therefore reliable lubricating effects between an inner wall of the center column B1 and the press member B3 can hardly be accounted. Above all, when such type of switch is electrically conducted, temperatures of the press member B3 and the contact plate C are elevated. The elevated temperatures melt and drain away the grease I accumulated between the lower end of the center column B1 and the outer surfaces of the press member B3, and thus lubricating effects are made even more unsatisfactory. Similarly, referring to FIG. 8, another type of press member B4 having a solid column also has the aforesaid drawback.
Referring to FIG. 9, the aforesaid press member B3 for switching is replaced by a ball bearing B5 made of metal materials. However, to assemble the ball bearing B5, grease is necessarily applied to outer surfaces of the elastic member B2 after placing the elastic member B2 into the center column B1, so as to temporarily adhere to the ball bearing B5. After placing the contact plate C into the switch housing A, the button B together with the elastic member B2 and the ball bearing B5 are placed into the switch housing A. During the assembly process, the ball bearing B5 not only is prone to fall off due to any slight contact, but may also be easily bounced away when sliding the ball bearing B5 into the center column B1 by pressing the elastic member B2. Therefore, assembly process of this structure is quite complicated while being time consuming.